Valve control for fluid levels in hydraulic power plants



Dec. 7, 1948. FlSCHER ET 2,455,747

- VALVE c TROL FOR ID ELS RAULIC PO PLANTS IN Original Filed Nov. 18, 1959 4 Sheets-She et 1 INVENTQRS: Howard R.F|5oh fdward. WSteve n 7, 1948- H. R. FISCHER ETAL 2,455,747

' VALVE CONTROL FOR FLUID LEVELS IN HYDRAULIC POWER PLANTS Original Filed N V. 18, 1939 4 Sheets-Sheet 2 Edward wstevens m/ M ATTORNEY.

7, 1948- H. R. FISCHER ETAL 2,455,747

VALVE CONTROL FOR FLUID LEVELS IN HYDRAULIC POWER PLANTS I Original Filed Nov. 18, 1939 4 Sheets-Sheet 3 INVENTORS:

I i Howard .Fiscner \\\X\\ \\\1 Edward Stevens I 180 Q BY 9 v ATTORNEY.

Dec. 7,, 1948. H. R. FISCHER ETAL 2,455,747

VALVE CONTROL FOR FLUID LEVELS IN HYDRAULIC POWER PLANTS Patented Dec. 7, 1943 UNITED STATE 5 PATENT OFFICE of New Jersey Original application N o vember ls; 1939, Serial No. 305,204, now Patent No. 2,365,536; dated December 19, 1944. Divided.and thisappiica-- tion October 21, 1944, SerialjNqfi 559,762

I The present application is a division of the copending application Serial No. 305,204 filed} November 18, 1939, now Patent No. 2,365,536,

issued December 19, 1944.

This invention relates generally to compression riveting and more particularly to a hydraulic control mechanism for a portable power generating unit adapted to have one or a plurality of riveting units attachedthereto.

According to a feature of the present invention,

the power generatingunit comprises, in addition to the hydraulic system for effecting operation of the riveting unit, a valvular controlled compressed air system for actuating the hydraulic system.

The principa1 object of the invention is to produce a hydraulic valve mechanism such asflan equalizing float valve forming part of a small controlled automatically, and which automatically terminates acycle of operation; p

2. Automatic means, capable of operation prior to the release of the manipulative trigger, for returning the power and riveting pistons to normal t it:

which the several steps of a riveting operation are p position, thereby speeding up operations in which a number of rivets are sion; and t t f 3. Control mechanism associated with the hyheaded in rapid succesdraulic system for maintaining automatically a in the various sections of elevation, of the power generating unit;

Fig. 3 is a view looking downward through the base of the power generating unit and is taken substantially along the line 3-3 of Fig. 2 or 4;

Fig. 4 is a sectional view taken substantially along the broken lined-4 of Fig. 3; t

Fig. 5 is a detail view of a certain valve control mechanism which functions to maintain a proper balance of oil in the oil reservoirs looking in the direction of the arrows 5 in Fig. 3;

l it 2 Fig. fi is as diagrammatic view and illustrates the machine in its normal position;

f Figl-l isa' diagrammatic detail view of the revaivein actuated position;

i Fig, 8 is afragmentary sectional view similar to 'Fig. 5 but on a larger scale, showing the upper andfthe lower valve for controlling the flow of oil between the reservoirs; and

Fig. 9is a view ofthe lower valve, chiefly in longitudinal section asindicated by the arrows 9 inFi'gv 8, andonthe same scale as the latter.

The rnachine is shown in Fig. 1 completely assembled and ready for operation. The riveting unit and the power generating unit are indicated generally therein by the respective numerals 20 and 2 I; 'lhe riveting unit 20 is connected to the power-unit 21 by a plurality of pressure fluid conducting hose lines and is adapted for manual manipulation, independently of the power unit,

anywhere within the range of the hose lines.

Each unit 20 and 2| is a complete assembly in itself but is formed of several cooperating sections or sub-units, each detachable from the other, to facilitate assembly and replacement, or servicing. The riveting unit 20 comprises, broadly, a handle 22;a cylinder 23,apiston assemb1y including a piston rod24, and a yoke 25. The several sections of the power unit include a head 26, in which the principarcontrol valves are mounted, an intermediate section comprising the main compressioncylinden2'l, and a. basesection 28 in which is formed the-oil reservoirs, pressure outletsand other elementsand mechanisms to be described later with greater particularity. The power unitis mounted upon casters 29 to permit theunitto be moved easily from one working pointto another. t t

ljIn constructing this machine advantage has been taken of all known mechanical expedients to, insure a maximum of efiiciency in its operation. In the specification therefore, no specific mention is made ordinarily of elements such as piston rings or seals, gaskets, and the like, but it should be understood thatthese elements are provided in the machine, wherever necessary.

Cons ldering first the riveting unit 20 and referring to Fig. 1, the handle 22 is secured to a portion integral with cylinder 23 and extending therefrom at an angle of about 45 degrees relative toythe axis of themain part of the cylinder. The handlefland cylinder 23 are secured together by means of screws (not shown) while a piston rod 24 extends downwardlythrough a bushing or cylinder extension 36 screwed into the lower end of the cylinder 23 and "overlies anvil head 49 on 3 yoke 25. Extension 36 projects below the cylinder 23 and the projecting portion thereof passes through ,theupper ,end. of the yokelfi .l oiorm an efiective :oonnection ibetween the extension land the yoke.'

Referring more particularly to the diagram;

matic form of the apparatus shown in Fig. '6,

plied directly to the upper end of prefill valve 83 through a port 88 connecting passage 14 and a chamber 89 formed about the upper reduced por- ;tion. of'pr.efill'-valve bushing 86. The .va'lve 83 is thus normally held downward, against the re- .sistance of a compression spring 9|, by line pressure acting on the upper end of the valve; it

"beinglunderstood that expressions such as uptherein and the valve 62 controls jthBfflOW .of air from the counterbore 65, throughthabore and out the port 66. The valve 62 is preferably urged per and downward, when used in this part of the description, refer to the positions illustrated'diagrammatically in said Fig. 6. Air is supplied .directly also to the lower end of dis-.

tributing .valveiil z by means of a passage 92 leading from main air passage M into a chamber 83"fOI'I'II8d'3Wll3hiIlfih6 closure plate Bl which enclosesthis end of the valve (see Fig. 2). A down .wardly extending rod 94 is secured to the lower to closed position by a spring (not shown) and.

normally prevents the :escape of air from the pounterbore 65. The throttle control trigger 63 is pivoted to an inner-sunface;ofthe'handle 22 and .is :adaptedto engage itheirearmostzendzof the valve 62. A clockwise movementof the trigger-63, of Fig. (6,, serves :to move {the .valve .52 to opened position. Nilith the valve -,B2 in opened position, air is permitted :to pass from {the counterbore 65 through the bore 64 and out the port1 66 to atmosphere. This escapeofzpressure fluid occasions adrop in iline pressureiin the g-powergenerating unit which, in a manner ilateritozbe described, conditions the machine 'fora .cycle of operation. .In Fig. 6, the valve 62 and trigger 6,3 are, shown in normal position.

Asshown in Fig. -1,- a hose line -69 ,is connected ito :the :base .;2 8.of :the power unit .21. -.Cornpre ssed .air, generated Joy ,means not shown herein, is introduced through'the hose line :69 into acham- ,berl l formed in the :loase 2:8. .E'rom the chamber ill the airpasses upward through a passage 1.2 iincylinder casin 2.1 :and into the head sec- :tion 26 through ;an inlet 13 (Fig. .6). Inlet 13 (opens into ,a longitudinalg-main air passage 14 .in head '26 and lax-tending into the main air qpassage is a hosecoupling @(not shown) to which is attached an intermediate throttle hose J6 -.,(Fig. 1,). As shown in said liig. 1 the hose 'Ifiextends gdownward and into -a two way valve assembly Ill, later to be described. Extending .irom the valve assembly H is'a'main throttle hose 18 connected to the .preyiously mentioned counterbore .65 formed in riveter handle 22. The line pres- .sure of :main air passage .74 is thus maintained, 1no rmal-ly, :also in ,counterbore .65.

Referring to Fig. ,6 constituting the diagram.-

end of the valve 82 and supports a collar 95 at .its llower end. Compressed between the collar 95 and an abutment 9B,.secured to the lower end .of,bi1shingt85 ,,is-a spring 91 whichlbymeason of its arrangement urges :the valve .82 ,downward, rtothe position shown in Fig, .6. Normally, vline pressure is acting also on the upperiend of valve .32; '.thereby,.balancing the pressure .below the valve, and .the spring 9.1 is .free .to hold thevalve downward .in the position shown. -If the .air pressure above the .valve.82 is reduced .below line pressure, the valve will be=f,orced.upward,.,against the resistance of compression spring .81, .a .disltance determined by the extent of the reduction oi-pressure above :the valve. Air is .directed .to 'theupperendpf distributing valve 32 through a .senies of ports and :passageways controlled by 35 the automatic return valve 8|. A port 98 .con-

imatic view, it will be seen that the several cOIltrol valves mounted in the head .25 comprise an automatic return valve 81, a distributing valve ,-8 2 and a prefill valve 83, so named for. reasons which will hereinafter more ,clearly appear. These valves are movable within respective cylinidrical bushings .84, .85 and 86, each of which is ,open at both ends in order that ,air may be ,in- .troduced' therein above and below its respective valve. Each assembly comprising .a. valve and valve bushing is mounted in a respective .bore in .head 26, the opposite ends of each bore being closed :by closure plates8l (Fig. 2.) appropriately formed to enclose the ends of the valve bushings .and to permit ,freedom of movement oi .the valves.

The valves .8I, .8,2. and :83are controlled by in- .dividual springs and .by pressure .fluid supplied .either directly or indirectly from air passage 14. Referring to Fig.6, .Whereinthevalvesare shown an normalpositienit :willb een that .airis supnects themain air passage 14 .toa groove .9.B-cut longitudinally .in the outer surface of return \valve bushing .84.. The air passes .from groove Qilatj ro gh .a pair of .ports llll in .the bushin 0 84, around a reduced portion of valve .8! and through :a. .port m2, formed .in the opposite side of the bushing, into .a second bushing groove i113. .Apassage .HJA .connects .the groove 403 to .a.,chamber 105 formed :about the upper reduced 4.5 portion of valve .bushinglifiand thus, in the normal position of .the parts, line pressure is sup- .pl-ied..constan'tlyv to the chamber M35.

.A ,metering Iorifice 1,06 is ,positioned within the air passage .14 intermediate the main inlet 13.and ,hose.coupling .15 so that the unseating of throttle control valve .62, in riveting .unit 29,, causes an immediate drop in pressure in the ,line between .meterihg .Qrlfice m6 and counterbore .65, since .the .air cannot pass through the orifice 1,06 zaszprapidly as it es apes through port .66. The extent of pressure reduction in this line ,is .determined by the extent of actuation given .the .tri gger'es .Port .98 communicates with .air passage 14 '.at .a point within the area of reduced .pressure.so that the .drop in pressure occasioned by operation of the trigger 16.3 is reflectedalsoin .theports and passageways leading to chamber llliiabove valve .82, and in the chamber itself.

In initiating a cycle .ofmachine operation the tri ger. .63 m y be fully actuated in a single motion' or .it may be momentarily held in a par- ,tially actuated position before completing the iull stroke, Since a riveting operation consists 'ofga firststage, in which the rivet is set, and a second stage, in which the rivet is headed, the operation of the machine will be described ,as consis in .of separate st s, he first of which .is initiatedhy a movement of the trigger 63 throu h. a portion of its stroke and the second upon the completion ,of the trigger stroke.

ji s fl mediate partly operated position, its upper end "still closes apair of portsI22 communicating distance upward Where it is held, byla second compression spring llll placed betweenaniabut- *ment collar I08 engaging the loweruend of the valve, and the previously mentioned .collar-sor spring base 95. In the normal position of the valve 82 the spring IO'Iis without erfectsinc'e no relative movement between the valve andthe collar I88 is possible unti11the collar engages the abutment 96. This occurs upon completion of .1 the initial upward movement of the valve 82 and it will be evident that further upward movement of the valve mustbe accomplished against the combinedaction of springs 91 and II". If the valve 82 is in the intermediate position, the-live .airacting upon the lower end of the valve is perjmitted to pass through a port I09, in abutment,

collar. 96, around the reduced lower end of the I valve and through a pair of ports II I into an annular; groove I I2: formed in the outer surface of the bushing 85. A passageway H3leads from the groove M2 to a chamber H4 formed around thereduced lower end of prefill valve bushing 86 so that upon I the initial movement of distributing valve 82 line pressure is established in chamber II4., Extendingffromp th'eqchamber H4 is a passageway H5 which leads downward through the intermediate section of the unit to the base I and opens into a prefill reservoir I I8 containing a suitable liquid, such as oil. Live air pressure acting upon theoil in reservoir H6 forces theoil through a passageway I I! into a pressure chamber H8 and thence through means, including whose ime H9, tohandle 22 of riveting unit. ,In

handle 22 the oilis driven into the upper end of piston chamber 34, forcing piston head 35 and ,rod24 downward to set the rivet. The hydraulic system is actuated at this time solely by air'pressure withinthe reservoir I I6 sothat the, pressure obtained in 1 pressure chamber 34 is relatively small and insumcient to actually head the rivet.

. Returning now tofa consideration of the prefill ally builds -up below the prefill valve 83 and, as

"the gradually increasing pressure counterbalances the line pressure acting on top of thevalve,

the spring 9| moves the valve upward. The ,upward movement ofthe valve 83 is further retarded by reasons of thefact that the air, above j the valve, can escape only through a narrow openingbetween the upper end ofthe valve bushing and the closure plate 81, similar to the opening between the lower end of the bushing and pro- I2I. If valve 83 occupies an interwith the upper chamber 89 which receivesjline pressure through port88 directly from the main air passage 14. When the prefill valve has movcd upwarda slightlyfurther distance, it will uncover theports I22, allowing air to flow through the ports around a reduced portion of th'evalve and through another pair of ports I23 into an annulargroove I24 formed in the bushing 88. The groove I28 is connected, by means of a pasge I25, to anannulangroQveYIZS formedinthe distributing valvebushmg 85. The groove I26 communicates with theinterior of the bushing through a set of ports I21 which are closed by the head of the distributing valve in its norma and intermediate positions.-

When operating the control trigger 83 in two steps the second step, to fullyactuated position,

is performed after the rivet setting stage of the operation and may take place before or after the ports I22 are uncovered by the prefill valve. Upon the trigger 83 being fully actuated with the throttle control valve 62 completely open, the drop in pressure between the riveting unit and the metering orifice I08 will be considerable, and, as, reflected in chamber I85 above the distributing valve 82, will be suflicient to permit the valve 82 to be :moved to its extreme upward position against the compression :of the two springs 91 and I81. This movement of the valve 82 from its intermediate position to fully operated position serves to uncover the ports I21 and permit air to flow through the ports around a reduced portion of thelvalve and through a second set ofports I28 into another annular groove I29, formed in the bushing 85; Communicating with the groove I28 isca passageway I3I which extends downward and opens into a main compression chamber I32 containing a piston assembly including a piston head I33 and rod, I34 Normally, and during the rivet setting stage of operation, the piston assembly in chamber I32 occupies the normal position shown in Fig. 6. However, upon the extreme upward movement of the distributing valve, line pressure passing through the above described ports and passageways enters the upper end of chamber I32 and drives the piston assembly downward.

Piston rod I34 extends downward into the oil pressure chamber I I8 and, in moving through the chamber, forces oil at great pressure through the passagewaysleading into riveting piston chamber 34 to drive the riveting piston assembly downward and complete the rivet heading operation. If, for any reason, it should be desired to prolong the rivet heading operation beyond the normal time in which this operation is performed, a means is provided for reducing the flow of air to the chamber I32 to increase the time required to build up sufiicient pressure therein to operate the piston assembly. I'his means resides in a set screw I30 adapted to engage the upper end of the prefillvalve 83 to limitthe upward movement of the valve. As shown in said Fig. 6, the, screw I 30 extends through the upper end of prefill valve plete, the trigger 83 may be released. Upon release ofthe trigger, the air in the passageway 18 between the riveting unit and the metering orifice I06 will build up to line pressure and this pressure can be used to return the distributing valve 82 to its normal position,- thereby cutting off the flow of air to the, main compression chamber I32 and prefill reservoir I ISL However, an automatic con- Itrolmeans, which acts independently of the trig- .ger 63, is provided for returning the valve 82 when a predetermined point of peak pressure is reached 6 in the chamber I32. In this connection, a second [passageway I35 opens into the upper end of the were??? r!il= e ixe stee l ;upward t a b ed untag ed valpassage 5!":2'1! -ini;oga chanib'er M2 ibelow ithe zuuto- :mati'c re'turn valve 13 l. The pressure fluid thus "Iintroducediinto :cha-mber W42 immediately forces lthe valve 3 :upwardaagainst the :resistance of a compression spring 143, into the position s'hown iinEFPig-FL As shownun't-he' latter figure, the valve, when in its upper position; "closes theport H12, :leading iintoigroove t 03, butestablishes-communication between this'groove and the inter ior of the bushing 85 a through another" port W4; Also formed' in the bushing 84, opposite the-port PM and opened by upward-movement f the valve; is :a port 44.45 4 communicating with a passageway M6 leading sdireotly drorn the ma in air-passage M. The passagewaydflfi "opens into the main "a ir passage at a point between the "air inlet 13 and mietering orifice 106 so that full -line pressure may ipass through passageway M6 andport +45 around-a lower reduced portion *of 'valve 8| and then through *por't 'l4'4- into groove "33. From groove #63 the air flows, of course, through pas- "sage 1 M into chamb'erlll'5' 'above "the distributing *va1ve82, forcing-this valve downward tothe nor- 'malpositionof Fig; 6 and thereby erasing ports 1'2! --and "I lto stop the flow" of pressure fluid to chambers 1'32 and I I6 respectively.

7 Still referring to Fig. '7, it will be seen that the air-of reduced pressure below the metering orifice MB-flows from groove 99 in bushing 784 through the upper one of the ports IOI, around the upper reduced portion of the valve =81 and then through "a passage I41, formed in the bushing, into a chamber I48 above the valve. Asthe airin chamber M8 builds upto a suflicientpressure to balance the pressure acting upon the lower end of the valve, the spring 1'43 returns thevalve downward to its normal position. This occurs upon the closing of the throttle valve .62.

In order to speed up the return action of the,

valve 8|, an auxiliary return-connection may be provided. Thebushing 84"is formed with a port M9, normally closed by'the Valve 8!, communicating' with apassage 'I5l leading'into an opening 15-2 (Figs. 6 and 7) from which extends another passage' I53 opening into the :main a'ir passage '14 below the metering orifice I06. jUpon upward "movement of the valve '8 l the flower'reduced portion thereof 'is placed Opposite the port M9 and line pressure passing'around this reduced portion from port I45 is admitted through the port .149 to-passages ll and T53. Ametering orifice I54 is-positionedinthe-opening I52 (Fig. 6') and delivers, at a restricted rate, compressed air into'passage"H'r3and1r1ose TB, thereby complementingthe action of orifice I06. I

It is also desirable, for'quick and efficient operation of the machine, that the relief valve 1.31 be returned to its seat immediately after it has ,per- 'form'edthe function of causing the operation of "valvetl to the Fig? position. To insure prompt action of valve I31, linepressure, when admitted through por't 1-49 m bushing 84, "is also admitted througha similarly formed port 5 (Fig. 7) to ra-passageway 156 leading into the bore I36 at a point-to the *rearof the valve I31. The combined actronriot the spring llts'zand zairiat line pressure ithus produces :an ample :forice for time raretumunf thezreliefrvalvenand chamber1M2, :below drhe waive dill, ..is positively cut off from the mhambalt' 1 32'.

'I'n corderithat the valve aBfl/rnay be zretainedzln itszuppen'zoriactuatedposition,iforfthe timeineoes- .sary to accomplish the :return -:of thezdisizributing .ivalve 102, asmeill npening l.5:1. (Fig. 6 :is formed :in' thG JIQWEP reduced portion of thenvalve' lfll wwhichcommunicatesrwith alb'ore H58 mlrillefldnathe slower zendxof ithe ivalve. Pressure ifluid from .iport '1 P athus ipasse'szalso lthrough thezopen'ing I l 5111mm :horeilr581into the tchamher. M2 :and actsrupon the slower end of rthe nvalvezli'l. After'the closing iof :relief valve 431 :air :is isuppliedctoiithe chamber #42'only throughithezopening 11521.. a v

111i, .and :as :long as, Ethe operator, l-subsequent to ztheicompietiomof :the 'rivetiheadingstroke o'f' p s- -tons l63rand35, continues to lh'old xthe throttle xzalvefl -open, the 1 automatic return waive 8 l will :be held :in its upper or operated .positiom il1us- 'trated.in d igf'llby the preponderanoe of the pressure of substantially live air, delivered through opening 151 and'bore 4'58, over -the'opposing com- :bined pressures of spring -143' and 'fiuid'un&er"a e- 'tluced pressure. Under these conditionssu'dh re- :duced pressure, in hose 1-8 and associated'passages, 1 does not initiate a new -cycle of operation asbefore, beoausethe =automatic-returmve1ve8 l is new positionedto deliver live air through passage 10'4 to the upper end of distributing *valve f82. Upon release of throttle valve 6i to closed positiion, air pressure in hose T8 buildsujttbjinebressure to balance the fluid pressures 'at the endsjfof valve 'SIand permit the 'springdfl torest'ore'iit tothe normal -(Fig. '6) position; The auxiliary passage W53, associated with metering drificejlill, performs an important;'though "rrot'iindispens'able, function *in augmenting the r'isein pressure in hose 18 with the consequentrestoration'df valve B l to normal, following the close of ithrottle valve Bl 'Th operator, therefore, 'may'reopen'fthe throttle valve to head a newgrivet without any appreciable 'd elay 'onacc'ourit of the restoration of valve 8] subsequent to the .closingoii 'theith'rottle 'va'lve. The return stroke of the main piston 1-33-'-.I'3fl fbegins v.immetiia'tely upon the return, of the distributing valve '82 to normal. Since the driving piston encounters less. resistance ,on its return than on its,power stroke, reduced'pressure may beusedfor its return, lthereby efiec'tingfia saving in compressed air. As shownin'Fig. itin the normal .position of the valve I82 rain. at ,line pressure, flows through a bra'n'ch I58 ,ofthe passageway 92 into an annular .groove lffl 'lfin distributing'valve bushing 85,. Fromgroove 3l5'l.',..the air passes through a set of ports (62, aroun d a 'reduced'port'ion of the .vaive 18 2 .and -b11t .a -St- 0f ports I 63 into a second annular groove-15.4. ,-A downwardly extending passageway [.55 "cates with the groove |6f4fland-abranch-1536,01 thepassageway 'leads into .a bore 16.! lformed ifn aprojecting porit'ion .ilfiffl of the cylinder 21 ,(see 'Fig. "2) Positioned Within the bore ,l-B'l, is.,a well-known type of reducing valv'enssenibly' J58, .hav'ing avalve 1.69 movable within albushing, If! I to control the flow of airin'to passage II'IL An adjustable spring .1113 presses upon .the ,lower-surfaQe of adiaphragm .IJAto urge the valve-lfiflrto open position While air entering ,the open. upper ,end of bushing 111' acts, upon the uplper. rend. .of "the valve, to close it whenthe diaphragmds forced downward, Thelairfiowsintotm uppenend oi bore Hi1, through a set of'ports' r16, i nthe bush- 9* ing I1I and past the valve I69Ito the passagel'l2; where it is directed to the lower end of bore I61 and out a passage I11. In passing from passage I12 to passage I11 the air acts on the upper surface of the diaphragm I14 and presses it downward against the tension ofspring I13. The valve I69 is thus allowed to move downward to-a partly closed position and, as a result,*the pressure of the air passing from the lower end of. bore I 61 is substantially less than that of the air entering the upper end of the bore. The passage I11 opens into the lower end ofcompression chamber I32, below the piston head I33, and the air of reduced pressure thus introduced-below the piston head serves to return the-piston to itsnor-I mal upper position. I I I II Provision is made for directingair, trapped on leading, in a manner not shown herein, to anex haust chamber I82 (see Figs. 3 and 4) formed in the base 28. Extending into thechamber I82; through anopening in the base plate IiIIl, is a muffler comprising a perforated retainer I83 filled with copper wool or a likesubstance. A closure plate I84 covers the lower endof the retainer I83 and exhaust air is permitted to pass through the I retainer and out openings I85 in the platedaflto atmosphere. Durin the downwardmovement of the piston I33I34, the distributing valve 82 is in its uppermost position and, as already discussed, the exhaust port I18 is then 'opposite a lower reduced portion of the valve and is thus in communication with the ports and passageways leading into the lower endof compression chamber I32. During this portion of the cycle; therefore, the air belowthe piston head las i's driven to the exhaust chamber I82, via passages I11, I66, I65,etc. I I 1 II It is also desirable that chamber II4, below theprefill valve 83, be connectedto exhaustin the normal position of the machine in order that the oil in reservoir II6 may returntolts normal level, Therefore, an opening I86 is formedin a grooved portion of the distributing valve 82 and communicating with the opening-isa longitudinal bore I81 in the valve. Infthe normalpositionm of the valve 82 (Fig. 6) the opening I86 therein lies opposite a pair of portsfl88, in the bushing 85, which communicate with the previous1ymentioned annular groove I I2i EXhaustairis then free to flow from chamberIM through the connecting ports and passagewaysito opening I86 and then through longitudinal boreI81 1 At the upper end of bore I81 anotheropening I89 is formed in the valve 82 and the air frombore I81 passes out this opening, around the upper .reduced portion of the valve and out theI exhaust -prtI18. I I

Turning now to a further consideration of the hydraulic system it will be rememberedlthat'the initial movement of the 'oil takes place during live air under the usual line pressure, say, 90* pounds per square inch, is admitted Ltd the I prefill reservoir II6. Then; during the second or the bore I91 is a bushing? l99 Iin which is mounted ing piston I33,I34 is actuated and the oilahead of the driving piston forces the riveting piston assembly downward to its operated position, Iwith a. pressure of several tons. In order that the rivetingpiston may be returned to its normal" po-I sition aftereach rivetheading operation, oil is supplied through passageway 33, in the riveting unit, to the lower end of the pressure chamber 34 below the piston head 35'. Referring again to Figfifi, there is provided in the base section 28 of the power unit, a return oil reservoir I9I into theupper end of whichopens the passageway I; {In the mentioned normal position of the? distributing valve 82, air under line pressure flows I throughthispassageway and thence through parallel branches to serve the dual purpose of returning the driving piston I33I34 and acting upon the oil in reservoir I9I to effect theI return of the, riveting piston. Reservoir I9I is in communication with an oil pressure chamber I92 in Upon the which is mounted a return piston I I93. introduction. ofliveair into thereservoir I9I the oil therein is forced downward into the pressure chamber I92Iwhere it acts upon the base of the piston-I93 to force it upwards. As the piston I93Imoves upward, oil above it is forced through, means including a hose line I94 to -tne riveting handle 22 where it is conducted by means of passageway 33 to the pressure chamber 34 where itreturns the piston assembly therein to the norair is conducted to thepassageway I65, are closed and:line I pressure is hence cut off from the reservoir I9I Further, the passageway I65 I is opened Ito'exhaust at this time so that no air pressure opposes the riveting piston as it descends tol its rivet setting andrivet heading positions.

I primary force in lowering the piston I93 is oil from the prefill reservoir I I6, introduced through aconnecting passageway I95 which opens into the pressure chamberl92 ata point above the head of the piston, both reservoirs H and II6 being disposed above the common bottom I96 of base'28; I I I I I I I I I ;I In order that a proper balance of oil may be maintained in the various sections of the hydraulic: system certain valvular control mechanisms are" provided. shownin Figs; 2and 3, thereturn ireservoir 'I9I and pressure chamber I92 are separated by a wall of the base casting, which does not, however; quite reach the base plate I88 and so permits constant communicationIbetweenthe lower end of the reservoir and the lower end of the chamber.- Referring particularlyto Fig. 2, the piston I93 is formed with a bore I'91"which extends throughout the length of the piston and communicates, through a pair of ports I98,Iwith the lower end of chamber I92 below the head of thewpiston. Supported within a valve 28I. 'I The valve 2IlI is movable within the bushing I99 to open and close aIpair of ports rlvetvheading stagesofthe=cycle, theimaimdrive? my .whichficommunication:is established I-be'liili t weenlthe bore Iflt .andxthezuppenendioffohamborr lfiflabove'thepiston 1831. The valve-wins urged) to: closed position by: a. compression spring 2033 extonding betweeni aishould'en offibusliing Ifliliand: an abutment 1 collar 20'41 secured tor-the lower: end! 01? the valve;- but, im the" operated. or' downward: position. of" the piston; theivalvei is. held iniopen positionby" reason of? the engagement oft collar' ZfillWith base: plate IBDH Tlieroperated D'QSitlOn': offtheassem'bly is' showrr. ii'nFigzi 2s and? it willfbez seen that, at: this time,:oil1mayl passfromr the: upper: endi oil the chamber I92; downward? throughitheaportsazflztinto thebore I91 and out the: ports-1 I98? toflthe lowerend of chamber: I92 and to: the reservoir." I91. Then; when'l com pressed air-"is admitted. to the resenvoin- IHItb initiate a returnst'mke'zofi the'rive'tingi piston; oil; passes: fromthe: reservoin through: the-a ports I88: into) the bore I91 and: out. the. ports- 2172': totho= upper 'end' of: the chamber I820 Whom therupper end ofi'the chamben'ismlled; theioillfrom themesenvoi'n I9.Ie acts.- upom the lowen'surfa'ce: of the head of piston. me and. forces thepiston upwardel Upom theiinitial upward movementtof 'thepistom. theiuppen encL of bushin'g I991 en'gageszthe head: of T valve; 2m thus: closing! the. ports 2M, and duning'th'e subsequent upwardzm ovementnfrthepise ton the-several? elements I93; IESta-nd 21": move: together as:munittandlthezvahte remainsin; elosed: position. The: oil; ahoveothe: piston? I93 issfnrcedi ontra passageway 205 which: openszintmthez upper. endioffohamber: I82 and connects, in: aimanneri' not shown hereim, to: the"; return oil hose: M311 (Fig. I).

im F'rg 6vis awliagrammatic2 representation on thei connection; effected; by passageways 206 and' ZIl'I- between the reservoir ISIS and charnben: I92:

Positioned) withini the. bore: 2'68 (Figs; 4;, 5,. 8 andi9) and: extending belowfit". into thezreservoir: I511 is atlilocle' 2.09; which: actsas a bushing. for! a" pair: of. oppositely disposed valves. 2H. and: 212: which o'ontrolzthes flow'cfr oil tiiroughainarrowr opening 24 a'in the brlonli. Ehevalves ZeIjI an'd 2.12:

Tare spaciedi slightly 'fromx the inner guide: walls:

ofitheehlockil flh'tmpennit the oil topass arounda bl'IHMZlVflSK opening 2l'3l Thevalve" Ziillis urgediupwardito closed position by: a sprin 244! and isdbm'nedwwithzalstemlor extensionlz Ifijwhicln 3 passessthrougltthec:opening/2J3 andsun'deriiesithe:

lower end of valve H I. With valvei izlainupper on closed; position;. the extension 21 5 thereof: engages-:thevalvelhl and" holds it offi it's seat in; opem positionz. As'i-shownirrFig, S-the mid-porftions oil the. valve? 212 and block: 292* are slottedl vertically to: permit; thepassage 'of' oil to and from thee-valve and to: receiveronexend; of aalevei 2A6: pivotedaatuZ FIL .to an inner walls of: the block. Tiheslemen 2 IE6? bears, at its left hand v end; as also; viewed: im Rig. 5,. as laterally extendingv stud' 2118,- w-hielr passesvthroughlan opening ZI 9 inlthe; valve: ZZIRzandzpmieots into at horizontal'slot 221' f onmedr im the: block. 205. The; valve 242 may thus' bei raisedand lowered upon operation of the lever Zl'B-WhlfihilSlIl'lOVfiblB about its pivot point 24;! 9A distance limited to: the rangeof: movement per-=1 mittedithe: stud 24 May the opposite" edges. of the slot. 214. Themighthand endi oi thelever 216; asiviewed-j in Fig; 5;.is; pivotally# connected to a;

Im the: pne'sent; hydraulic: systemiuasz ire-those: 3'57 rodx 222'; secured to the": lower: one of. a p

of: a. similar class; to certain; amountc of: oil: seep"- age takesiplacei-about the pistorrheadlfi in: the

chamber: 3A: In general}. the seepage: in; oneidirrectiom past; thm pistoniisfi oounteracted'l by; seem age: in: the opposit'edirection during. a1 different. part of theacyclesbut; as azpraotieaizmattemreal; equality balanoeo is: rarely lfli even attainedi. inzthe; present instance, the: amounttof oil which seeps. from! the; upper: end: of. chamber. 34' tmits lowerrendiduningv extended "openatiomofi the machine exceeds at donsiderablei amount:- tha seepage: which. takes: place during. the: same: pm" nod. in! the: opposite-direction; Also, .if' the; map chihe stands. 1:11am a. protracted perimiL. with: the ainpressure turned omoihwill pass from: the: lower end: of. chamber: 34-; tor the: upper end .azndi none atalllreturn inztha oppositezdireictiom Ex oessivaseepagesin.eithendirectionxpashthfipistom head 35.-will' causaavariationinthe normal leveil of; the oil; withinhreturm'reservoir' MM. Shuulcb this level go too high the oil may overflovwintoi the ainpassages-a andlif! tha' leveh goes;- tcrol low! the suppi'y therein; may; he: insufilcientz to; operate: the: returni pistonl H932. Wide. variations: on thee levelin reservoir: IQIi are;. therefore, undesirablm and, im orderrtosoonfine variations withimnarrow liinit'st certain; addition'ai; control; mechanism. is: provided; in accordanoe with the present inven tion., Assshawnaimlligss. 3;.4 andrfi; thezretumi reservoin Ia and: the? pneflll: reservoin' IIG: are: connected; a: pair of; passageways 20% andi 2M, therla-tterrof". whi'clt is imoommunibation with: or bone. 208; (Fig; 49? opening; intoz: the: reservoir lfldz. The. passageway 20.1: communicates: adsmwithithntpressures ohamhen I52: (seeEi'gsizzarrdi at a:

ahovesthez heart. of: piston I83; ,smthat, dun-- ihg: thee prefiilr operatlom. oils passes fromrthe: resenvoir: I Iii: through the: passageways: 20R .and:' zlil. andzaots:.to;-return the: I93Sdbvmwarfi; The previouslwmentionedlpassagewayz IB-E,

46 I8I,.as previously: describe.d;.oi1 will pass from'the reservnirr I-I- through the-topening: 2 I34 past valve: 2H and through the passages ZII'I-andiZllBz to the prefill reservoirr M6; the; pressure: of the" oilbeing sufiicientr to' unseat-waive 2;I ll As the oil level: thussdm-psin reservoirl NH, thelever 2:I6.-is1caused2 tn'move ini alclock-wise direction (Fig; 5) and valve- 24 2 is; urgedi by spring: 21 4 to closed positionin' which position, the extension 21'5- thereof will. maintain v-alva 2J4: off its sea-t. When live airpressure isithen-applied'to the-prefill reservoir, as; previouslyidesoribed; oil .from the prefilllreservoir. will pass downward :througntheopening 2;I 3 and: amund' valve: 212 into the return reservoir. Im order thatlthevaive' 2I2 may= be unseated-at this time-.toanzextentthat willlallowthe passage of: oilipa's-t-iit',.it is; permittedar. slight movement or lost motlomrelatively-tortherlever 2H5; Itwillbe notedIthatithe-opening 2I9 inthe valve (Figs. 8; and 9-) thmugh=which= the'stud 218- is passed, is; of: slightly; greater: diameter: than the stud. The valverMQ,.whenrtheslever'hassmoved.to its allowezb limit in a clockwise direction, is held in its fully, olosedtpositiombx'the; spring 2M whilethe' stud 2-1 fliisiheldi a: short: distance-below; the upper; edge ofr the: opening: 2.1m reason: ofv its; engagement? with the: upperr edge? of: the 51012224. But; the? valve) 24 2 ,,in.;response to: the oil pressure:- from reservoir Izlfiland'uagainst thezresistance of spring, ZlIMWilhbe mnvedzdownwardia distancesuflicientt tmpermittoihtoiflaw/downwardzthmughzthe:open;

Manure ing' i [3; even though the lever 2 l6 and buoyant elements 223-=bein their lowermost positions. The relative downward movement of the valve M2; at this time; is not enough, howevento perniit the valvelll toreturn toitsseat. Valve 2| I will close only when the buoyant elements 223* riseandpull valve ZIZ a further distance off its seat. In the'interval before valve! ll closes, the

desired ainountofoil will flow from reservoir M6 to reservoir fl 9l.

"The exchange ofoil between the prefill reservoir and the return reservoir thus takes place when compressed air is admitted to these respectivechambers, and it will be noted that, by

'reasonof theconstruction of the valves 2| I and 212; an eiichangepf oil will i take place during eachcycl efof machineoperation. The valves 2H and2l 2 cannot occupy their seats at thesametime and it is always possible to force oil in one direction or theothenthro-ugh the opening 2|3. When live air is admitted to prefill reservoir H6 duringthe rivetsetting p ortion of the cyclepoil is' iorced past the valves 2H and 2| 2 until the oil lev'el in "the return reservoir rises to a point where valve 212 will be pulled fullyoff its seat and alve2ll permitted to drop to closed posi tion. Then when air under pressure is admitted to the return reservoir ISI, during the piston return ornormalizing portion of the cycle,

oil isfdrcedin the other direction past the valve 212, unseating valve 2! Land continuing intothe green-reservoiruntu the oil level in the return reservoir drops sufliciently to permit valve 2 l2 to move to fully closed positions If there is an excessiveamountof oilin the return reservoir, the

valve 2 l 2 remains open for a period longer than nerm'eiwn there is alack of oil in the return reservoir; a='correspondinglylonger time is required to pull valve 2l2 off itsseat, during the rivet settingstrokaand additional oil may flow from the prefillreservoir past the open valve 2| I. "Foran easier understanding of the foregoing explanation of the valve mechanism, the following fldiagram will be helpful. 1 The various posi tions of the essentialparts of thevalve mechanisrnfandthelevels of the reservoirs are shown,

thecycle of operationsbeing assumed tobegin when the prefill reservoir is at high level and the return reservoir is at low level with the buoyant elementandthe outer endof the leverin down or lowered position. i

I-intermediate (position in which valve 212 is down to the extent permitted by the lost motion arrangement between stud 218 and opening 219).

Stage 1.Instant air pressure is first applied to oil in prefill reservoir at the beginning of the rivet setting portion of the cycle (column 13,

line 21 et seq.). Stage 2.--Instant valve 2 I 2 is forced down against spring 2|4 to extent permitted by lostmotlon between opening 2l9 andstud arrangement Stage 3.-Period duringwhich oil is passing from" reservoir MB to reservoir l9l. l

Stage 4i--Instant of completion of transfer of oil' to reservoirlSl;

Stage 5.Instant air pressureis applied to 011 in *return reservoirat the beginning of the piston return or normalizing portion of cycle (column Stage (Ee -Period during which oil passes from reservoir 9 I to reservoir I I6;

Stage 7.--Instant of completion of transfer of oil 151' *toreservoir H6, V l

l been previously described how the peak pressure obtainable in the compressionchamber I32 maybe varied by operation of the adjusting screw [38 (Figs; Sandi?) to vary the pressure with which Ithe relief valve I31 is urged to closed positiori. 113 is desirable to vary the peakpressure obtainablekin the chamber I32 since; by this means;;each riveting operation may be performed withamaximumwof efliciency. In heading rivets of differentsize thescrew I39;is set in accordance with the size of; the rivet to raise or lowerthe air pressure within the chamber 132;; It will be evident that by reason Of;thiS adjustable means a considerable savingqof time and compressed air 11 isleifected. To assist the operator in determining;- the proper setting of the screw I39 for each size; rivet aw standard pressure gauge (not shown),- maynbe affixed to the machine and caused to r register thedegree of pressure within the cham-U,

'WhiIe the invention has been described swith; particular reference to operation of a riveting machine,it is susceptible of operating machines for other uses, such as pressing, pullingtorushing,

punching andembossing. 1 v What isclaimed is:

t 1, In a hydraulic system, the combination of a cylinder, a motor piston reciprocable therein, a pairofpoil reservoirs in communication with the respective endsof said cylinder, means for apply ing airypressure in alternate ones of said reservoirs to actuate said piston, a passageway connecting said reservoirs independently of the cylinder; a buoyant element floating on the surface ofthewoil intone ofsaid reservoirs, andcmeans controlled bysaid buoyant element for controlling the flowvof oil between said reservoirs, said means acting in one position of said element to prevent. the now of oil in one direction through said passageway and acting inanother position of said elementto prevent the flow of oil in the opposite direction through said passageway.

=2i In ashydraulic system; the combination of a cylinder, a motor'piston reciprocable therein, a

pair of oilr'eservoirs in communication with the respective ends of said cylinder, means for apply-v inglair pressure in alternate ones of said reservoirsz' to actuate said piston, a passageway connecting said reservoirs independently of the cylr indena flrstmeans settablerto efiectiveand in-;

effective positions for controlling the flow of oil in one direction through said passageway, and a second means settable to effective and ineflective positions for controlling the flow of oil in the opposite direction through said passageway and operable when in efiective position to set the first settable means in ineffective position.

3. In a hydraulic system, the combination of a cylinder, a motor piston reciprocable therein, a pair of oil reservoirs in communication with the l5; respective: ends; ofisaildr cylinder;.meanslifor applyingrairrpressurein; alternate ones of. said reservoirs to actuate said piston, a passageway connecting; saidi reservoirs independently, of the cylinder, a first means:settableto-eflective andiineffective positions: for; controlling; the: flow of oil 1m one direction through said passageway assecond means settable to; effective and ineffective positionsxfoncont-rolling: thBIfiOW! of oil: im the opposite dicectiom through said: passageway and operable when in effective position to setsaidi first settable means in: ineiiective position, a yielding. means urging said secondl settable means; to effective position,. and: means-1 movable; in response. to changes in the oil level of one ofisa-idreservoirs for setting said second settable means in ineffectiveposition'i 4.- In a hydraulic system, the-combination of a pair of oil reservoirs in communication with each other, means for applying pressure in alternate ones of said reservoirsto" effect an exchange of oil hetween sai'd reservoirs; a first-means settable to" a position effective to prevent theflow of oil in" one direction between said reservoirs and to another position in which it permits the flow of oil" in said one direction; a second means settable to a position effective to prevent the flow of oil in-the-opposite direction between said reservoirs and to anotherposition in which it permits the flow of oil insaid' opposite direction and operable cylinder, a' motor piston' reciprocable" therein, a-

pair of oil reservoirs in communication with the respective ends of said cylinder, means for applymg ai'r' pressure in alternate ones-0f said reservoirs to actuate said piston; a passageway connecting said reservoirs independently of the cylinder, a first means settable toefiective and'ineffective positions for controlling the flow of oil in onedirecti'onthrough said passageway, a second means sett'a-bleto a plurality of positions in afirst of which it' prevents the flow of oil in the opposite direction through said passageway and sets" said first settable means to ineffective position; and: ina second of" which it only sets the first saidmeansin ineifective position; andin: a third of whi'ch it is ineffective toperform: either of the abovefunctions, meansmovabl'ein response to: changes in the oil level in said reservoirs for:

pair of oil reservoirs i'n communication with; the respective ends of saidzcylindenmeans for apply-' ing: airpressure in alternate. ones of saidires'envoirs: to actuate said: piston, a passageway conmeeting: said: reservoirs independently: of the; cyb' inder, abuoyant element floating. on the surface? of the oil in one. ofsaid reservoirs, and; means"; controlled by said buoyant. element for' control. ling the fiow'of. oil between said reservoirasaid: means. acting in one position. of said element to: prevent the'flow of oil in one direction: through said passageway and acting in another position. of said element to permit the'flow of. oil in: the: same direction through said passageway-..

7:. In a hydraulic system, thez-combinationzoti'a cylinder, amotor piston reciprocable thereim, a, pair of oil reservoirs in communication withithe;

respective-ends ofsaid cylinder, meanslfor apply ingpressure in alternate ones ofsaid: reservoirs toeffect an exchange of oil between said reser Voirs'upon movement of the pistonandseepagei past the piston, a passageway connecting said] reservoirs independently of thecylinder, abuoyant element floating on the surface ofthe-oil'in:

one: of. said: reservoirs and avalve,-.mechanism-r controlled bysaid buoyant element. comprising, a

valve block having limitedbores axial. alignment therein, communicating means betweenithe; bores having valve seats at itsoppositeends, a. check valvemember freely mounted in one of. said-bores-and adapted tobe opened in. response.- to oil pressure'in a first direction andto be closed by gravity,. a second valve member. mounted. inthe opposite bore and having-a portion extending.- through the communicating means to underlie: the-check valve member, spring means constantly urging the second valve mem'ber t0. seated posi-- tion, pivotally' mounted lever means: controlled at its outer end by t-hebuoyant. element, a stud mounted-on theinner end of the lever formingaa 10st mot-ion connection with the second valvew member, and slot means arrangedto cooperate with said stud to-limitthemovement-0f the lever,

,said' lever being adapted upon motion in one direction in response to the elevation oftha buoyantelement -to.- unseat thesecond valve .member against: the resistance of thespring. means,. andupon motiorr in the other direction response to the'lower-ing of the buoyant element-to permit the seating of the secondvalve member. as urged bysaid spring means, said lever being,

further adapted when inone. limitedv position to limit the movement of the second valve member to'the extent permitted by the 10st motioniconnection.

8. A combination, according to claim 7, in which the lost motion connection comprises an aperture in. the second valve member having. a

3 diameter greater than the diameterof the stud.

HOWARD'R'. EDWARD W. srrzvrzns...

REFERENCE-S CI'DED UNITED STATES PATENTS Name Date Ashworth Feb. 18;. 1941 Number 

